Since communication systems are more and more widely used, demands for reliability are becoming more and more prioritized. Reliability may relate to a risk of failure when a message is delivered to a first network node from a second network node.
Signalling System No. 7 (SS7) is known to be used in for example a Serving General Packet Radio Service Support Node (Serving GPRS Support Node or SGSN) and the like. SS7 supports a distributed SS7 stack, which employs so called horizontal distribution. A protocol within SS7 is a signalling connection control part (SCCP) protocol.
A known SCCP protocol comprises a distribution function, also referred to a distributor function, which distributes a message received from a second network entity to a corresponding SCCP instance. The SCCP instance is identified by a SCCP instance identity. The message is received on a SCCP connection, which is identified by a Local Reference. Furthermore, the SCCP instance holds state information for the SCCP connection, thereby tying the SCCP connection to a particular SCCP instance. Moreover, the SCCP instance identity is encoded in the Local Reference. When the distributor function receives a message on the SCCP connection, it decodes the Local Reference to obtain the SCCP instance identity. Thus, when the SCCP instance identity, has been obtained, the distributor function may forward the message to the SCCP instance identified by the SCCP instance identity.
If the identified SCCP instance is turned off for some reason, such as maintenance or failure, a disadvantage with the known SCCP protocol is that messages on the SCCP connection to the identified SCCP instance may fail. Thus, there is a need for an improved SS7 protocol, which overcomes or at least reduces the above mentioned disadvantage.